Looking over the magento 1.5 schema I cannot seem to figure out how a product_id relates to an entity_id.
In all my test cases I can verify that the product_id and entity_id are equal (the same int). But I am guessing that somewhere this is a relationship and even though they are equal in my test cases, it's likely this is only a coincidence and not something I should depend on.
In what tables or relationships can I find what this link is so that I can write a reliable query.
I'm just looking for something like this... tho it probably won't be this simple.
select entity_id from <wherever> where product_id = 1234
As per Magento forum post by a Magento Team member entity_id on the EAV side is in fact the same as the product_id on the catalog product end. So, there you go.